GSTM1 and Beta-thalassemia: Also, Winichagoon et al., in their study on 144 patients with beta-thalassemia were divided into mild (46 patients), intermediate (55 patients), and severe groups (43 patients) reported that Two alleles of mild beta-thalassemia mutation β+β+ thalassemia or β+/Hb E) resulted in a mild clinical symptom whereas two alleles of severe beta-thalassemia mutation β°β°produced a severe clinical phenotype45.